Achieving full shutdown with new Kernel?

Recently I cross-compiled a new Ubuntu kernel based on the v3.12.x branch according to Robert Nelson’s fantastic work and instructions resulting in a build 3.12.5-bone10.1.

This was also used to compile a kernel module providing support for an Asix usb ethernet adapter.

All working excellently (great usb support now) apart from the system not completely powering down; the power led remains on (from e.g. shutdown -h now).

Is there some patch available to solve this problem?

Best wishes, Ron